The present invention relates to a jack capable of selectively accommodating a plurality of types of plugs for communicating signals pursuant to different data communication standards; to a reproducing apparatus incorporating the jack; and to a data communication system including the jack.
Recent years have seen widespread acceptance of such digital audio equipment as MD (mini disc; a registered trademark) systems or DAT (digital audio tape) recorders. The digital audio equipment records and reproduces audio signals as digital audio data to and from a storage medium such as a disk or a magnetic tape.
Portable MD systems, DAT recorders and other portable digital audio equipment are also well-known. Typically, portable digital audio equipment requires connecting to the equipment body a set of headphones worn by a user to hear reproduced sound. Generally, a remote controller is provided as an operating part between the headphones and a plug. The remote controller allows the user to perform various operations including playback without directly manipulating keys on the equipment body. A display part may be located close to the controls of the remote controller, allowing the user to check the current playback status and other operating conditions.
Generally, the headphone cable comprises a plug-equipped line for data communication between the remote controller and the digital audio equipment in addition to an audio signal line. The data communication line is connected by the plug to transmit operations by the remote controller to the digital audio equipment and to give indications on the display part of the remote controller.
The equipment body includes a jack as a connector into which to insert illustratively a plug of the headphone cable. The plug and the jack both have electrodes for audio signal transmission and for data communication for use with the remote controller.
Recently, a communication standard called TSB (time sharing bus) is used extensively as a data communication standard addressing remote controllers. The TSB addresses data communication between a master and a slave device. Communication through the TSB involves the use of four lines: a ground line, a data line, a key input line, and a power supply line. The key input line conveys information to the equipment telling the latter which keys were operated on the operating part. The data line transmits contents to be displayed primarily to the display part in the form of serial data. There is no dedicated clock line; a clock signal is tapped from the data line. One-bit data is illustratively made up of a 12-unit serial data part, each unit driven High or Low for 16 .mu.s (16.times.12=192 .mu.s), and a clock period of a High and a Low level, each level lasting 16 .mu.s (16.times.2=32 .mu.s). That is, one-bit data has a length of 224 .mu.s (=192+32), corresponding to a transfer rate of about 4,464 bps. With the TSB, eight bits constitute one byte. Ten bytes of data make up one packet. Prefixed to each packet are a sync signal indicating the beginning of the packet, a request signal requesting data between the master and the slave device, and a direction signal designating the direction of data sent from one device to the other.
The digital audio equipment above is capable of inputting and recording digital audio data to a storage medium and outputting to the outside digital audio data reproduced from the storage medium.
A data communication standard IEEE (Institute of Electrical and Electronic Engineers) 1394 providing for data transmissions as fast as 100 Mbps may be adopted for the input and output of digital audio data. Where functions addressing such a high-speed data communication standard as opposed to the TSB are to be incorporated in MD systems, DAT recorders or other portable digital audio equipment, the following problems can arise:
For example, suppose that the data communication functions based on the IEEE 1394 standard are adopted by portable digital audio equipment. This requires adding a connector compatible with IEEE 1394 to the equipment.
Adding a data communication connector anew to the portable digital audio equipment is disadvantageous since the equipment needs to be made smaller than ever for enhanced portability. As it is, the equipment will have difficulty allocating space in which to accommodate any connector compatible with IEEE 1394.
Conceivably, the data communication connector mounted on the existing portable digital audio equipment could be used unmodified as a dual-purpose connector additionally addressing data communication pursuant to IEEE 1394. However, this option is not very practical. The reason is that the TSB communication standard is currently used for data communication between the existing portable digital audio equipment and its remote controller and that there is no compatibility in terms of physical specifications or communication protocols between the TSB standard and IEEE 1394. Generally, it is very difficult to make the connector serve for a plurality of applications if their physical specifications and communication protocols are not in common. Meanwhile, where two units of digital audio equipment are to be connected for data communication, each unit needs to be furnished with batteries, an AC adapter or like power supply resources in order to ensure the separate supply of power to the individual units. As today's portable digital audio equipment is getting smaller in size, connectors on the equipment also need to be made smaller. This can promote fragility of the set of portable equipment connectors as opposed to large connectors of stationary type equipment.
It is therefore an object of the present invention to overcome the above drawbacks and disadvantages of the prior art and to provide a jack capable of addressing a plurality of data communication standards without occupying additional connector space on equipment, as well as a reproducing apparatus comprising that jack.